Integrating movement behaviours for intra-specific conservation: The caribou case

Abstract

Conserving diversity below the species level is vital to maintaining species' adaptive potential. However, defining intra-specific units for conservation is complex due to the often-continuous nature of differentiation, and thus multiple lines of evidence are needed to adequately capture adaptive differences. Caribou (Rangifer tarandus caribou) exemplify this challenge, exhibiting diverse behavioural, genetic, and morphological variation throughout their range, with several populations facing extirpation. We used a long-term telemetry dataset of 302 caribou across the species' range in western Canada to assess individual variation in movement behaviours. This included behaviours hypothesized to be of adaptive significance, such as migration, home range size and shape, and inferred predator avoidance tactics. Gaussian finite mixture models were then used to identify intra-specific behavioural clusters which may be evolutionarily significant, followed by Random Forest models to discern behaviours driving differentiation between clusters. We identified six distinct clusters based on individual variation in behaviour. Differentiation between clusters was significantly influenced by selection for canopy cover (%) at calving events, home range size and shape, migratory behaviour, and geographic location. Since behavioural variation arises from genetic, environmental, and social factors, our results highlight the value of incorporating trait variation into the assessment of evolutionarily significant units for conservation. We advocate for the consideration of behavioural variation, as it offers valuable insights into adaptive differences. This approach holds promise for informing conservation efforts, not only for caribou, but other terrestrial species at risk given the importance of maintaining genetic and phenotypic diversity.